import {
  clampDiceCount,
  createInitialDiceRollState,
  formatDiceNotation,
  isDiceSides,
  rollDiceValues,
  type DiceRollEvent,
  type DiceRollState,
} from '../../shared/types/diceRoll';

export class DiceRollSessionStore {
  private state: DiceRollState = createInitialDiceRollState();

  getState(): DiceRollState {
    return this.state;
  }

  clear(): DiceRollState {
    this.state = createInitialDiceRollState();
    return this.state;
  }

  dispatch(event: DiceRollEvent): DiceRollState {
    switch (event.kind) {
      case 'clear': {
        if (!this.state.active && this.state.values.length === 0) return this.state;
        this.state = {
          ...createInitialDiceRollState(),
          revision: this.state.revision + 1,
        };
        return this.state;
      }
      case 'hideOverlay': {
        if (!this.state.active) return this.state;
        this.state = {
          ...this.state,
          revision: this.state.revision + 1,
          active: false,
          startedAt: null,
        };
        return this.state;
      }
      case 'roll': {
        if (!isDiceSides(event.sides)) return this.state;
        const count = clampDiceCount(event.count);
        const values = rollDiceValues(count, event.sides);
        const total = values.reduce((a, b) => a + b, 0);
        this.state = {
          revision: this.state.revision + 1,
          active: true,
          notation: formatDiceNotation(count, event.sides),
          values,
          total,
          startedAt: Date.now(),
        };
        return this.state;
      }
      default: {
        const _exhaustive: never = event;
        return _exhaustive;
      }
    }
  }
}